Wood-Plastic Composite (WPC) decking boards have been in the marketplace around the world since the mid 1990's and arguably account for approximately 10% of the world decking market.
Despite the fact that the WPC's are generally more expensive than all but the most expensive timber, they have achieved huge inroads due to their perceived advantages being:—                Low maintenance (very good “life cost” value)        Very stable (won't warp or twist)        Environmentally friendly        Long lasting        splinter and rot resistant        
Being a man made “extruded” product, it is possible to make any shape that may be made via conventional plastics profile extrusion. Whilst most decking boards are substantially rectangular in the shape of a standard decking board, because of the inherent stability of the board it has become fairly standard to extrude boards with grooves in the side of the board to allow a “biscuit-type” fixing to be used to hold down the boards from the sides—thus eliminating the need for screws and nails to be used through the top of the board. This makes for a very aesthetically pleasing look to the deck as the fixing is substantially “hidden”. Biscuit clips are generally made from some type of plastic—they come in a large range of “proprietary” shapes and sizes but substantially have a centre section where the screw goes through, and a wing on each side that sits into the groove of the decking-board on either side of the clip.
However, biscuit clips tend to be quite fiddly due to having to fit the “biscuit” into the groove in the board and the drive a very small headed screw in between the boards. It is a two-part process as the screws cannot be fully tightened until the following board is laid.
Most screws used in the biscuit clip systems are specific, and are not suitable for use with either hardwood or steel joist systems making them very difficult to use in at least one of these environments depending on which screw is fitted to the biscuit clip in the manufacturing process.
Biscuit clips generally require “double joist” to be used at butt joins due to the minimal holding length of the biscuit.
Biscuit clips tend to be relatively cheap but relatively inefficient. Therefore, it would be a distinct advantage to the decking board manufacturer to be able to maintain a current board/groove product, but offer in addition a fixing system that was significantly more efficient in terms of speed of fixing, thereby providing the customer with a speed versus labour choice when using their boards in the marketplace.
A fixed pitch, continuous clipping system has many advantages over a biscuit-clip type system, including being much faster, less labour intensive, easier to work with, and eliminates the possibility of run-out. However, the one potential disadvantage of the fixed-pitch continuous clip system is that it is somewhat reliant on the decking boards being quite consistent in size. Unfortunately, due to the very heavy reliance on recycled feedstock, which in itself varies significantly, not all manufacturers of WPC decking are able to offer the consistency of size that is generally expected from man-made, extruded products. As such, boards of varying size, especially those that may be classed as “undersize”, can sit rather loosely in a fixed pitch clip. This is not ideal in the marketplace.
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